Alternatives; use your own judgment: PR Stanley wrote:
--count the occurrences of char in string countC :: Char -> [Char] -> Int countC x xs = sum [1 | c <- xs, c == x]
-- Direct mind-mapping of my brain: countC x = length . filter (c ==) -- Avoids constructing an intermediate list? I dunno. Looks stupid: countC x = foldr (\c s -> s + if c == x then 1 else 0) 0
--count occurrences of chars in string countCS :: [Char] -> [(Char, Int)] countCS xs = [(x, (countC x xs)) | x <- [' '..'z'], (countC x xs) > 0]
-- What popped into my imperative little brain import Data.Map(assocs, empty, insertWith) countCS str = assocs (countCS' str) where countCS' [] = empty countCS' (x:xs) = insertWith (+) x 1 (countCS' xs) -- but Stuart's pointfree version is so much nicer. Devin